In December, I put the 2015 Subaru WRX through its paces along some incredibly challenging roads in northern California, and to say I walked away impressed wouldn't really do my feelings justice. Say what you will about the way it looks, the new 'Rex is an awesome car, full stop. When it comes to all-weather sports sedans that won't break the bank, it's very tough to beat the WRX.

But then there's its big brother  the STI. The winged wonder. The rally superstar. The car that, to many  and to me  represents all that is right in the world of dirt-and-gravel thrills. Sharp as the WRX has always been, the hardcore STI model has always been a little bit sharper. But in recent years, that hasn't always been a good thing. What I've liked most about the WRX is the fact that it's not an always-on attack missile  it can be forgiving, easy to drive, and if I'm honest, reasonably comfortable. Because of that, in the WRX/STI debate, I've preferred the former for daily driving activities. I've always had a thing for That Wing, but in the outgoing car, the STI was never really far and away a more rewarding car to drive, and it offered exactly zero upgrades in terms of comfort or refinement.

The 2015 WRX is easily the finest example of Subaru's hot hatch sedan to date. But what happens when you try to turn the dial past 11? I headed back to NorCal, including a stop at the historic Mazda Raceway Laguna Seca, to find out.

A quick personal note: I'd like to thank Subaru for bringing back gold BBS wheels for this 2015 STI. The blue-and-gold combo is iconic on this car, especially with that giant wing out back. You can't get these rollers on the standard 'Rex, and while they certainly aren't for everyone, I can't picture owning an STI without 'em.

That said, not all STIs will be a gold-wheeled affairs. That's limited to the special Launch Edition  just 1,000 will be offered, only in WR Blue, during the first three months of the 2015 model's production. Other Launch Edition goodies include a short-throw shifter (available as an option on other models) and blue trim inside the cabin. More on that stuff in a minute.

A lot has been said about the design of the new WRX, and it hasn't all been positive. But the more I look at the new model, the more I like it  especially compared to its predecessor. It still isn't pretty (has there ever been a "pretty" Subaru?), but the new WRX's design works better here in STI guise. The STI's schnoz is easier to look at thanks to its more aggressive lower front fascia treatment, and its larger 18-inch rolling stock (wrapped in 245/40R18 Dunlop Sport Maxx summer rubber) better fills out the wells at all four corners.

Dimensionally, the STI is exactly the same as the standard WRX  180.9 inches long, 58.1 inches tall and 70.7 inches wide, riding on the 104.3-inch wheelbase of the Impreza. Aside from the redesigned front end and the massive functional wing out back, other visual changes are simply limited to the appropriate badging around the exterior of the vehicle. All STI models come standard with LED headlamps (they're optional on the WRX), and to give them a slimmer appearance versus the outgoing model, their turn signals have been relocated into the lower fascia directly above the foglamps. The look of the STI is a bit more cohesive than the base WRX, but again, not exactly pretty or balanced. Park the two models next to each other, and it totally seems like this car was first and foremost designed to be an STI, with things stripped away to create the less-powerful model.

Subaru will offer the STI in three trims  base, Launch Edition and Limited  the latter of which adds amenities like full leather seating, a premium Harman/Kardon audio system, a power driver's seat, and a moonroof. Regardless of which model you choose, the STI's interior is largely carryover from the WRX, save things like specific dash trim, a unique steering wheel, a different shifter, and slightly different seats that now use Alcantara surfaces with red accents (or blue, on the Launch car pictured here).

Visually, the STI's interior is... fine. It's nothing to write home about, but all of the controls and instruments are well laid out and easy to use. Of course, like the WRX, some of the plastics found within the cabin really aren't as upscale as they ought to be, especially considering the $34,495 starting MSRP, but the seats are comfortable and nicely bolstered, the flat-bottomed steering wheel is pleasantly thick-rimmed and a joy to toss, and all of the other major touch points are, again, fine. My biggest gripe with the outgoing STI had always been its downmarket cabin, and while this new car isn't vastly better, it's a step in the right direction. It's not nearly as stylish, quiet or refined as what Volkswagen offers in the Golf R, but it's downright luxurious compared to what's found inside the now ancient Mitsubishi Lancer Evolution.

There's ample space for four adults (or five, if you must), and while Subaru regrettably won't offer a hatchback version of the STI, the company is quick to point out that the rear seats fold down to create a pass-through from the trunk, which itself can easily swallow 12 cubic feet of cargo. Like the rest of the Impreza line, the STI's interior feels open and airy, with great visibility all around. Even with that big wing out back, it's easy to get a clear view of what's behind you. Subaru's optional navigation system works well enough, though it's still not as good as what other automakers are offering, and on the infotainment side, there's nothing particularly trick to speak of. It's all very simple, this STI, and while that might seem like a downfall in this oh-so-connected age, it's sort of refreshing. This car says, "stop fiddling with your touchscreens and smartphones, and just drive, already."

After all, that's where the STI really shines. Unlike the WRX, which uses a new 2.0-liter turbocharged boxer-four borrowed from the Forester, the STI is powered by the same 2.5-liter engine as before (though with a slightly retuned ECU), offering up 305 horsepower at 6,000 rpm and 290 pound-feet of torque at 4,000 rpm. As far as weight is concerned, the new STI only weighs two pounds more than the outgoing model: 3,386 in total, with the Limited model adding 58 pounds of heft. Because of this similar weight, Subaru estimates a 0-60 time of 5.1 seconds for the STI, which like the engine specs, is unchanged from the 2014 model. Fuel economy also stays the same, the STI netting 17 miles per gallon in the city, 23 on the highway and 19 combined.

Back to that 0-60 time for a moment  the STI's number is only 0.3 seconds quicker than the normal WRX, and a lot of that comes down to exactly how the power is delivered. In the WRX, the 258 pound-feet of twist comes on as low as 2,000 rpm, while the STI doesn't fully deliver its thrust until higher in the rev range. The winged sedan suffers a bit more in the way of turbo lag compared to its less-powerful sibling, but Subaru has retuned the throttle response to at least make the experience seem a bit punchier. The company's engineers say that, at 25 percent throttle input, the STI delivers more response than a 50-percent input in the old car. In other words, there's more oomph available closer to initial tip-in, but the experience doesn't come off as sudden or non-linear. The throttle is easy to modulate, and the STI feels properly quick, with a greater sense of urgency than the normal WRX. Subaru's SI-Drive system is also part of the STI package, with Intelligent, Sport, and Sport Sharp modes that alter throttle mapping depending on the driver's demands.

As before, the only transmission available in the STI is a six-speed manual, and it's great, especially with the short-throw kit fitted to the Launch Edition. During my drive along the notoriously windy Carmel Valley Road south of Monterey, CA, it was plenty easy to click between third and fourth gears, with the occasional plunk into second for high-revving power exiting turns. With the previous STI, I always found the clutch pedal to be slightly heavier than I liked, but that isn't a problem here. Your left foot will surely thank you if you ever find yourself slogging through rush-hour traffic in an STI.

Carmel Valley Road is a real treat, with endless switchbacks and a large number of elevation changes and increasing/decreasing-radius turns. But unlike so many other wondrous Californian backroads, the pavement surface isn't the smoothest at times, and that's a particular point of roughness  literally  in the STI. Of course, you expect this car to be a bit harsh  stiffer than a WRX, at least  so it's not out of bounds. But here, the 22-percent stiffer front spring rates (only 6-percent stiffer out back) were noticeable and not always welcome. There isn't much in the way of chassis forgiveness, and on rougher stretches of road, the rapid-fire undulations can get old, especially from the passenger seat.

A lot of that is easy to forgive, though, considering how nicely tuned the chassis is on smoother surfaces, or a track. What's more, the STI's steering is truly wonderful  Subaru still employs a hydraulic power-assist setup here, with a quick 13.1:1 steering ratio, compared to 15.1 from the old STI and 14.5 in the new WRX. Feedback is excellent, and this is easily the most go-kart-like Subaru I've driven to date  even more so than the smaller BRZ coupe. Manhandling the STI around corners is far more rewarding than it is in the WRX, and the level of separation between the two cars, particularly in the steering, is greater than ever before. Every action in the STI really does feel more precise, and more urgent, even if it does risk more neck aches on broken surfaces.

Following the jaunt down Carmel Valley Road, Subaru let us loose at Laguna Seca for a few hot laps. (Blue STI at Laguna Seca? Talk about a Gran Turismo fantasy come to life.) And here, all of the specific tuning that makes an STI an STI really came into play. Full disclosure: Subaru did swap out the stock brakes on our track cars for upgraded race units  normally, the STI uses Brembo stoppers (13.0-inch ventilated discs up front with four-piston fixed calipers, and 12.4-inch ventilated units with two-piston calipers out back), and on my road drive, there were no signs of fade or a lack of adequate stopping power. But since we were really hard on the cars at Laguna, the added braking power was great to have.

In addition to the new active torque vectoring all-wheel-drive system, the STI gets another bit of increased electronic wizardry for 2015  the Multi-Mode Driver Controlled Center Differential (DCCD). Upon startup, the STI defaults to a standard 41/59 front/rear torque split, with three different driving modes that alter the behavior of the system as necessary. Full Auto mode is what you'll want for the vast majority of daily driving  even spirited runs. But on the track, Auto - (minus) was our best friend, making less use of the center differential to hold more torque toward the rear more frequently. On the opposite end, Auto + tightens the limited-slip differential, for better control in the wet, or on gravel/snow. There's even a full manual mode of the DCCD, like the previous STI, with different center diff locking levels up to a straight-up 50/50 split. Combine that with traction control that offers a Trac mode that allows the wheels to slip a bit (the system can be turned off, too), and the STI's track attack prowess is better than ever.

No matter what your hottest Gran Turismo lap times look like, Laguna Seca is a challenging, rewarding course in person, and the STI is right at home here. There's simply a ton of grip available with the active AWD system, and with the engine cooking at high revs in third and fourth gears, the Subaru absolutely storms through the corners. The whole driving system inspires a ton of confidence, encouraging you to push the STI harder and harder with each passing lap. I haven't had the chance to track a WRX in similar fashion, but judging by its road performance compared to the STI, I don't think it would be nearly as good here.

That's a very good thing, though it makes the WRX vs. STI argument even tougher to debate. The winged Subie isn't a completely different beast, but it's far more aggressive than before, with greater precision and a stronger sense of performance urgency. The STI is no longer just slightly sharper than the WRX  it's a far more rewarding experience from behind the wheel.

Where the debate starts to move in favor of the WRX, however, is price  STI models start at $34,495, not including $795 for destination, compared to $26,295 for a WRX. Match a WRX Limited against a similarly equipped STI and you're looking at an $8,500 difference  $39,290 versus $30,790. For my money, I can't help but think I might want to just snag a WRX and put that extra coin into some goodies from Subaru's performance parts catalog or the aftermarket (hello, gold wheels). Or maybe I'd just spend it on a more refined, equally powerful Volkswagen Golf R. But the giddy, raucous, hooligan tendencies of the STI make it really special, and smiles-per-mile go a long way here. It may not even be the best WRX for the money, but it's hands-down the most fun.

Interior definitely looks better than the predecessor. While it looks somewhat mature and refined, it still has boy racer cabin. The D wheel and integrated boost gauge are awesome features. Hope aftermarkets get their hands on WRX/STI soon.

Good news! The rally-bred Impreza is back! Pat Devereux straps into the 300bhp, 4WD turbo-loon

So what's it like to drive?

Predictably banzai. Our first drive of it was at Laguna Seca racetrack where the STI felt totally at home, if a little breathless. Even working the engine as hard as possible the chassis didn't feel even slightly stressed. Steering feedback is definitely improved - if still quite detached - and there's a healthy dose of lift-off oversteer available with everything switched off.

On the road, the STI feels much the same as on the track, but you immediately feel all that new stiffness in the chassis. Every bump, lump and crack is telegraphed to not just your hands, but your back and backside, too. This is exactly what you want when you are blazing to your next destination in an imaginary hurry, but progressively more painful after about an hour of the same.

Which is exactly the way an STI should be: hard, fast and grippy. Preferred settings: Sport; Traction; DCCD manual with no bias.

Should I buy one?

There are other cars that are faster, more exotic and/or more premium. But none of them offers the same offbeat combination of rally-bred performance and handling like the WRX STI. If you like your console driving games, you'll love this car.

Weight is almost the same as the outgoing base model, at 3386 pounds, and the boxer engine is plenty familiar. The 2.5-liter turbo puts out 305 hp at 6000 rpm and 290 lb-ft at 4000 rpm.

The one-two combo of Laguna Seca’s long front straight, which rises spookily over a blind crest, and the slow, deep Turn 2 speak plenty about how the STI handles power and weight. By the time you’ve arrived at the off-camber braking point at the end of the straight, your heart is in your throat. There’s power aplenty across the range, and the STI feels lithe and balanced through Turn 2’s double apex. You have to work hard to induce understeer, and it’s easy to correct a bad line.

Only 1000 examples of the Launch Edition -- with those gold-painted forged alloy wheels --will be sold for $38,190. The STI Limited, at $39,291, has a few more feature comforts but adds more than 50 pounds of weight.

So the real questions become: How badly do you want the semi-affordable, hard-edged sports car of your dreams? And how stable is your relationship, anyhow?

Our test car, a $38,190, one-of-1000 2015 Subaru WRX STI Launch Edition model, came equipped with a short-throw shifter, hands-free keyless access, and blue interior trim highlights. Its biggest draw, however, was the WR Blue paint and gold, BBS forged wheels. While the wheels are available in silver on other STIs (standard wheels are cast), bizarrely, you can only get gold rolling stock on the Launch Edition. It’s a strange decision by Subaru, considering how iconic Subaru’s 555 WRC cars are.

You may wonder why gold wheels aren’t offered on the non-Launch Edition, or why the 2.5-liter is still being used, or why there’s no hatchback, but those thoughts don’t last long from behind the wheel. Offering far friendlier commuter behavior than the rapidly aging Lancer Evolution and greater fun around a track than the outgoing Golf R and its undefeatable stability control, the STI continues to be an enjoyable, capable, and intriguing outlier of a car.

The 2015 Subaru WRX STI is the fastest new Subaru you can buy. This rally race ready street car is fast, fun and iconic. In another accurate, fun and informative TFLcar review Nathan drives and reviews 2015 Subaru WRX STI near Monterey, California.